A pest is an organism which is detrimental to humans or human concerns. Pests include insects, plant pathogens, weeds, molluscs, birds, mammals, fish, nematodes (roundworms) and microbes.
Typically, pests are classified into insects, mites, nematodes and gastropods. Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest. A pesticide may be a chemical agent, a biological agent (such as a virus or bacterium), an antimicrobial, a disinfectant or a device used against any pest.
Pesticides are categorized into four main substituent chemicals: herbicides, fungicides, insecticides and bactericides. Pesticides can be classified by target organism, chemical structure and physical state. Pesticides can also be classed as inorganic, synthetic, or biological (bio-pesticide). Bio-pesticides include microbial pesticides and biochemical pesticides. These include pyrethroids, rotenoids and nicotinoids. Pesticides can also be classified based upon their biological mechanism function or application method. Most pesticides work by poisoning the pests.
An insecticide is a pesticide used against insects. They include ovicides and larvicides, used against the eggs and larvae of insects respectively. Insecticides are classified in several different ways. Typically, they are classified as systemic insecticides, contact insecticides, natural insecticides, plant-incorporated protectants (PIPS), inorganic insecticides and organic insecticides. The commonly known insecticides include: i) organochlorides such as DDT, aldrin, chlordane, chlordecone, heptachlor, methoxychlor, pentachlorophenol and the like; ii) organophosphates such as acephate, azinphos-methyl, bensulide, chlorethoxyfos, chlorpyrifos, diazinon, dimethoate, disulfoton, ethoprop, fenamiphos, parathion, trichlorfon and the like; iii) pyrethroids such as allethrin, bifenthrin, cyhalothrin, lambda-cyhalothrin, cypermethrin, cyfluthrin, prallethrin, transfluthrin and the like, iv) carbamates such as aldicarb, bendiocarb, carbofuran, carbaryl, dioxacarb, fenobucarb, fenoxycarb, isoprocarb, methomyl and the like.
Further, various plant derived insecticides are known such as anabasine, annonin, asimina, caffeine, carapa, cinnamaldehyde, citral, deguelin, eugenol, myristicin, azadirachtin, nicotiana rustica (nicotine) peganum harmala, quassia, and the like.
Azadirachta indica (Neem) is a tree of the mahogany family Meliaceae. It is one of the two species in the genus Azadirachta and is native to India, Pakistan, Bangladesh, Iran and grows in tropical and semi-tropical regions.
Neem oil typically contains nimbin, nimbinin and nimbidin. The seeds of neem contain a complex secondary metabolite known as azadirachtin.
Various parts of the neem tree have long been used in India for their medicinal properties such as anthelmintic, antifungal, antidiabetic, antibacterial, antiviral, contraceptive and sedative. Neem is also used for the treatment of urinary disorders, diarrhoea, fever, bronchitis, skin diseases, septic sores, infected burns, hypertension and inflammatory diseases.
Although all parts of the neem tree appear to have natural resistance to pests and diseases, the seeds appear to have the greatest resistance. Formulations and extracts of the seeds are effective against many species of crop pests, including gypsy moths, Japanese beetles, aphids, tobacco budworins and boll weevils.
Azadirachtin
Azadirachtin is a tetranortriterpenoid botanical insecticide of the liminoid class extracted from the neem tree (Azadirachta indica). It is a highly oxidized tetranortriterpenoid which boasts of a plethora of oxygen functionality and comprising an enol ether, acetal, hemiacetal, and tetra-substituted oxirane as well as a variety of carboxylic esters.

Azadirachtin is biodegradable (it degrades within 100 hours when exposed to light and water) and shows very low toxicity to mammals (the LD50in rats is >3,540 mg/kg making it practically non-toxic).
Mode of Action of Azadirachtin:
Azadirachtin is structurally similar to insect hormone “ecdysones”. These hormones typically control the process of metamorphosis when the insects pass from larva to pupa to adult. Azadirachtin mainly acts as an “ecdysone blocker”. It blocks the insect's production and release of vital hormones. As a result, insects cannot molt. Azadirachtin is also known to disturb mating and sexual communication of insects, repel larvae and adults, deter females from laying eggs, sterilize adults and deter feeding.
It is known in the prior art that compositions containing fatty acid ester salt are useful insecticides. The potassium salt of a fatty acid causes cuticle disruption of insects.
Some representative patent documents which disclose insecticide compositions containing either fatty acid ester salt per se or Azadirachtin as an active ingredient per se are discussed herein below.
European Patent No. 0862861 discloses a composition for killing thrips which comprises i) at least one fatty acid ester selected from the group consisting of glycerin diacetomonolaurate, glycerin monocaprylate, glycerin mono/dilinolate, sorbitan oleate, diglycerin oleate, propylene glycol monooleate; and ii) a non-ionic surfactant such as polyoxyethylene alkyl ether.
U.S. Pat. No. 5,346,698 discloses a composition comprising avermectins and related compounds such as abamectin in combination with one or more substituted or unsubstituted, saturated or unsaturated fatty acids or their salts.
US20050244445 discloses an insecticidal composition comprising i) at least one essential oil selected from the group consisting of corn mint oil, cedar oil, cinnamon oil, citronella oil, clove oil, corn oil, garlic oil, lemongrass oil, linseed oil, peppermint oil, rosemary oil, soybean oil, neem oil, thyme oil, orange oil, lemon oil, lime oil, grapefruit oil, tangerine oil, D-limonene, eugenol, geraniol, and palmarosa oil; and ii) soap which comprises potassium salts of fatty acids.
U.S. Patent No. 20090258950 discloses an insecticidal composition comprising: (a) 0.1-2.0% of potassium salts of fatty acids as an emulsifier; (b) 0.1-2.4% horticultural oil; (c) 0.1-1.2% cinnamaldehyde or cinnamon oil equivalent; and (d) 0.1-1.2% eugenol.
U.S. Pat. No. 5,001,146 discloses a storage-stable pesticide composition comprising a neem seed extract solution containing azadirachtin wherein the solution is characterized as having at least 50% by volume of aprotic solvent and less than 15% by volume of water said solution being non-degrading to azadirachtin
U.S. Pat. No. 5,409,708 discloses a fungicide formulation comprising a fungicidally effective amount of clarified neem oil which has less than 1.0 weight percent of azadirachtin.
U.S. Pat. No. 6,733,802 discloses an emulsion comprising a biologically effective amount of azadirachtin in an essential oil and a surface active agent, wherein said emulsion is made from naturally occurring materials and is devoid of synthetic compounds.
None of the compositions disclosed in the prior art patent documents are able to control a wide variety of pests in an effective way. Furthermore, none of the patent document discloses a synergistic pesticidal composition containing a combination of the substance derived from Azadirachta indica plant and non-plant based material which is economically efficient and ecologically safe.
Commercially available insecticides commonly comprise active ingredients or poisons which are not only toxic to the target insect pests, but are also toxic to humans, if used in relatively confined environments and delivered as aerosol sprays. Various undesirable side effects may include immediate or delayed neurotoxic reactions and/or suffocation. Even the noxious odor of such materials can cause headaches or upset stomach in some individuals. These adverse side effects are exacerbated when such compositions come in contact with persons of increased sensitivity.
Despite the use of known pesticidal agents and compositions, there still exists a need for an economically efficient and ecologically safe insect control composition. The growing outcry against the use of hazardous insecticidal compounds has necessitated a need for a novel pest control method and/or insecticidal composition which can reduce the amount of pesticides necessary to obtain acceptable levels of control. Researchers have experimented with various combinations of various constituents as one approach to identify compositions which have desirable insecticidal characteristics. However, the probability of finding a combination with synergistic effects by this approach is very minimal.
In view of the above, there is envisaged in accordance with the present disclosure an environmentally safe synergistic pesticidal composition which is effective at lower dose.